Friday, January 20, 2017

Starduster BMJR E36 Build Report

How I selected the BMJR Starduster kit for my second e36 electric free flight model starts many years ago when someone sent me a completely built ½ A glow powered free flight model less the glow engine. I only knew this person through emails but they must have thought I needed the model more than they did. For years it sat in my basement, I did have a Cox TD .049 but just didn’t get around to completing the airplane. A couple of years ago I thought I would try e36 electric free flight and ordered the electric components from Hank Nystrom – Texas Timers and bought a short kit for a Pearl e202.

BMJR Starduster e36
Structure of Starduster

My progress on the Pearl was really slow even with Hank gently trying to prod me to finish it. Then I came up with the idea of putting the electric equipment in the 1/2A model I had, turns out the model was a Starduster. For me having no experience with power free flight it flew pretty well, granted being a larger model it did not climb anywhere near as fast as an e36 model. After enough flying of that model, Hank convinced me I needed to finish the Pearl. My inexperience was more of a handicap getting the Pearl flying well but by the end of last year I had made many great flights with it and still have it in flying condition.

1/2 A Starduster Converting to Electric

Pearl e202 in Flight

This winter I decided I would have another complete e36 model flying and decided on another Starduster, this time one that was designed as an e36 model.  The BMJR kit is a full kit with an instruction booklet although I was able to build the Pearl fine from just the plans. Harry Grogan designed the e36 version and the construction was somewhat different than other models I have built. The wing has angled ribs that connect with the straight ribs way before the trailing edge. Thin 1/64” plywood is used to tie top and bottom spars together. The wing and stab appear very rigid before covering although somewhat heavy compared to the Pearl.

Wing and Stab Construction Starduster
Fuselage Construction

Fuselage Fitted for Timer

Covering for the fuselage was Esaki tissue; wing and stab were transparent Micro Lite. Electronics came from Texas Timers which is what I had used in the Pearl e202. I find the eMax electronic timer very easy to use and it has been completely reliable. In the Starduster I was able to use the provided plywood plate with a little modification and all of the gear fits inside of the fuselage. For power I am using the AX 1806N electric motor as I used in the Pearl, this is plenty powerful for my skill level.

Texas Timers Components 

Front of eMAX Timer

Sal Taibi the Designer of the Original Starduster

I seem to have a fascination with models and modelers of the past; the original Starduster was designed by famous free flighter Sal Taibi in 1958. Interesting reading can he found on the Academy of Model Aeronautics website in a document that is combination autobiography and biography. Several modelers have relayed found memories of Sal such as him driving his 56 Chevy to contests or testing an ignition engine by grabbing a live spark wire. 

Bill Kuhl

Related Links  Sal Taibi on AMA website  BMJR Models Starduster e36  Pearl e202 E36  Texas Timers  eMAX timer and accessories  ½ A Starduster with electric

Wednesday, January 11, 2017

Building the Wilbur NOS Rubber Model

One of the things that have kept me interested in the model aviation hobby for so long is the great variety of model airplanes and the many challenges provided by the different types of models. I started flying control line airplanes as a youngster, then radio control (RC), RC sailplanes, and more recently free flight model planes.  Within free flight there is a HUGE variety of model types and contest events. Last summer I went to my first Nats at the International Modeling Center in Muncie Indiana and flew in several free flight events.

Wilbur Rubber Powered Free Flight Model
Jim O'Reilly

There appears to be a trend of wanting to relive the past or in my case I feel like I missed out on certain types of model airplane experiences and I want to try them in the present. After meeting Jim O’Reilly at the 2016 Nats who competes in rubber powered events and runs a model plans business, I decided to contact Jim for suggestions of an older model design that I would build. The model I selected was the Wilbur which was designed in the early 1950’s. Besides the excellent plans Jim creates he has partnered with Bob Holman for laser cut short kits. With a short kit the main parts are included and you provide mainly strip and sheet balsa.

Building a model with all the diagonal pieces was not as hard as I thought it would be, but connecting the two sides with more diagonals was more of a challenge. Apparently I did not connect the sides correctly, in my mind I thought the angles should fill the gaps instead of meeting together. The fuselage although very light seems really rigid just the same.  How the stabilizer was built with diagonals and straight ribs seemed like overkill. The cut out in the vertical fin where you insert another piece with the grain going at 90 degrees was a clever idea I had not seen before, I assume this is to prevent warping.

Vertical Fin Keyed to Fuselage

Covering Fuselage With Polyspan

Folding propeller construction is completely new to me but I purchased a blank from Volare Products for this particular model. The rough shaping and the hinges come done in the blank so it is mainly final shaping. On a model this size there is a ball bearing thrust washer and a shaft bushing needed which I ordered through FAI Model Supply. The fuselage was covered with Polyspan and the rest with Esaki tissue. I was worried how flexible the wing was until I had covered it.

Folding Propeller

Bushing and Bearing

Band Burner DT

For a dethermalizer (DT) I am going to try a rather hi-tech new device which is a band burner DT. This is an electronic device that will burn through a small rubber band at the time you set. I plan to report on this more after I have tried it. 

Also I have provided link to S.A.M., - The Society of Antique Modelers
“The Vintage models flown by SAM members are those designed, published or available as kits during the golden era of model aviation, the decade of the thirties to the beginning of WWII.” Quote website

Bill Kuhl

P. Visser's "Wilbur" Nostalgia Mulvihill per Zaic '53    Item ID  NOSR9   Propeller Blanks  FAI Model Supply - bearings and bushings Band Burner  SAM - The Society of Antique Modelers  Academy of Model Aeronautics

My 4 Minute Video of 2016 FF Nats

Tuesday, January 3, 2017

Model Flying in 2017

New Years day in Minnesota turned out to be good model flying weather for January; low wind and temperature right around the freezing mark. The day started out sunny but that faded away early afternoon.  In the morning I flew my Fantastic Foam Flyer rubber powered plane early from a schoolyard when the temperature was only 23 degrees F. I had just painted it with Design Master Floral paint to give it some color against the snow or a cloud covered sky, I think it helped the visibility and did not add much to the weight.

In the afternoon I went flying at a larger field and had some longer flights with the FFF, the short video clip shows what it looked like in the sky with the red paint. I then put out my hi-start to fly my Sig Riser 100. Pounding the stake in the ground was not easy for the first couple of inches. For the next hour I made launch after launch but just couldn't seem to find thermal lift that my glider would climb in for very long. The hi-start was snagging in the ice so many of the launches were not very high. Landing repeatedly in the icy snow tore a couple of holes in the Monokote covering.

Sig Riser 100

Pounding Hi-start Stake

After putting the Riser away I flew a free flight CLG (catapult launch glider) for a few flights. On one flight it appeared to be in some lift and drifted to one edge of the field and landed in a low bush. How it got around other branches and landed just as it did I do not know. After that I made a couple flights of my small Icon A5 seaplane from the snow.

FF CLG Landed in Bush

On Monday it was windier but I flew the Icon A5 again, I had so much fun skipping it across the snow doing repeated touch and goes. When I finished flying I happened to look at the bottom of the plane and it was full of scratches and gouges in the foam. It was repaired by epoxying some foam in large gouges and then clear tape over the bottom of the hull.

Hull of Icon A5 Showing Damage

I Flew With Gloves on

I also tried out the used Walston tracking system I had recently purchased. The tiny transmitter was left in my car and then I experimented with listening to the beeps at different distances and transmitter angles.

Walston Tracking System

Turning really cold again now but I have plenty of model building projects going on.

Happy New Year

Bill Kuhl

Wednesday, December 7, 2016

Sky Demon e20 Build Report

My interest in the e20 electric free flight event came about mainly because I am looking for free flight models that will fly from smaller flying sites. With electronic DT (dethermalizer) it is possible to accurately set the time that the DT will actuate. I have flown my e36 free flights from pretty small fields by setting the DT time to be short. It was my thought also that a model that only weighs around 30 grams will survive some pretty hard landings without damage.

BMJR Sky Demon

Before selecting an airplane I purchased the electric components from Bob Selman at BSD Micro, I knew of Bob from his tiny micro RC components and our mutual friend Floy Richards who passed away several years ago. I purchased a 2.5 gram unit that controls the motor run length and the DT time, the actuator for DT is a tiny servo that moves in one direction. I built a small pivot arm that one end goes under the servo rod that moves and the other end connects to DT line.  With my purchase I also selected the programming box, a Parkzone motor, a propeller, and one battery.  From flying tiny RTF RC planes I have many chargers.

BSD Micro Motot/DT Unit

BSD Micro Programmer

For my first e20 airplane I decided I would build a balsa kit airplane and selected the Sky Demon from BMJR.  This plane looks like it could be a tiny RC plane because it has a full width fuselage; my thought was if I got tired of flying it as an e20 I could install tiny RC gear in the plane. I installed  the motor/DT unit on the outside of the plane with a couple of screws so it could be easily removed.

Motor, Propeller and Battery

EZE Dope

Building the Sky Demon was easy although some of the pieces were rather small and I had to use a tweezers to place them. I covered with Esaki tissue but tried a new to me product EZE Dope to seal the tissue, it doesn’t give off the odor that clear dope I normally use. It did pull the wingtips up when it tightened up giving them washout that I thought might be a good thing. The plane has a left turn under power and glide so I think one wingtip has too much washout.

Sky Demon in Flight
Sky Demon DT in Progress

Last weekend the wind was rather low although it was only 32 degrees F but I decided that was warm enough for test flights. The motor run was set to only 4 seconds and the DT was rather short but long enough to observe the glide. After launch the plane wanted to climb rather steep and to the left, so I launched banked to the right. The firewall of the motor was taped on so I could adjust it later, since then I gave it more downthrust and some right thrust.

Wing and Stab

Stringers in Rear Rather Small

Many flights were made; I am guessing probably around 15 although all were rather short. The plane appeared to fly in a stable manner although the transition from power to glide was not perfect. This will give me something to work on when I fly it again. The DT worked perfectly in those flights although sometimes it was only a couple of feet above the ground on DT.

DT Stab

I am providing the link to NFFS provisional rules for e20. Basically the airplane is limited to 20” wingspan, direct drive brushed motor and 30 grams minimum weight. My airplane weight slightly over 31 grams which I thought was good for a first build.      page 10 E20 Provisional Rules
Bill Kuhl

Related Links  - Sky Demon kit on BMJR website   2.5 gram Motor/DT unit  Programming Box  About Floyd Richards  EZE Dope Video

20 Second Video of Timer / DT

Friday, December 2, 2016

Building the Retro Gnome FF Hi-start Glider

How I decided to build the Retro Gnome hi-start free flight glider has a rather round about history. As my interest in free flight models has increased so has my desire to experiment with different aspects of free flight, in this case it was dethermalizers (DT).  My start with DT’s was with the viscous type which although lightweight, suffers from accuracy issues especially as the temperature changes. I had used the plastic clock windup mechanism that I purchased from Hank Nystrom in water rockets to deploy the parachute and it had worked well. Normally this mechanism runs through rather fast but it is possible to slow it down by putting very small weights on part of the mechanism that vibrate quickly and slow down the unwinding. Some people build their timers like this but I purchased the Micro DT from Hank.

Retro Gnome Farmework

Small Weights on Plastic Clock

To test out the Micro DT I decided I would install it in the free flight hi-start glider that Hank had shown on his website with the timer, the Retro Gnome sold by Retro RC.  I met Mark Freeland (Retro RC) at the 2016 Nats and he showed me a sample of the glider. 

Kit Components

Building the kit is relatively easy as it is laser-cut and there is an instruction manual, in some places the plans and pictures are a little small so I used a magnifying  glass, not going to say I am getting old. The wing seemed like it was not very rigid before covering so I used a technique Dohrman Crawford uses of using some reinforcing tissue strips over the structure before covering with tissue. The finished wing feels plenty rigid.

Wing Structure Before Joining

Fuselage and Stab

This glider uses a simple autorudder that  is pulled to the right by a small rubber band and to the left by a monofilament  line with a pin holding the tension until the pin is pulled out as the tow hook releases and the tow line pulls the pin out. As this is a hi-start glider a very thin rubber strip and line with a small flag make up the hi-start launching system, I purchased this from Retro RC also.

Kit and Launcher

My hope is to do some glide testing of the Retro Gnome this weekend and take additional pictures but no hi-start launches. The glider must be adjusted so that it goes up on tow straight, when the pin releases it should turn right because of the autorudder.  The design includes adjustment screws for rudder movement, stab incidence change, stab tilt, and a tow hook that can be positioned in multiple  locations.

Almost Complete

Stay tuned for future flight reports.

Bill Kuhl

Related Links

Friday, November 18, 2016

Model Airplane Building in Full Swing

Although it has been warm enough to fly model airplanes outdoors so far, the daylight hours have dwindled until it is getting dark just as I leave work.  My evenings are now spent building model airplanes for next flying season although last year I flew some outdoors all winter long.  For next year I am building a variety of competition outdoor free flight model airplanes. 

Wilbur NOS Rubber Model

Selecting models that introduce me to new building techniques that I have not yet tried in previous models makes the build even more interesting, or I might try a new covering type that I have not used before. After going to the 2016 Free Flight Nats and meeting Jim O’Reilly I decided I wanted to build a nostalgia rubber powered model. Jim gave me some recommendations and I settled on the Wilbur rubber model that was designed in the 50’s. This introduced me to a type of fuselage construction where the fuselage was constructed almost entirely of angled strips of balsa. It was a fair amount of work but the fuselage is amazingly rigid.

Polecat X Wing


In the 2016 flying season I flew a beginners P30 model the NJAPF at the Nats and two smaller contests, it worked well for me but it is not considered a super high-performance model. I had previously had purchased plans and rib kit for the Polecat X P30 designed by Don DeLoach so decided to build that model for next contest season. This model introduced me to carbon capped ribs and building a rolled balsa fuselage, I have not attempted the fuselage yet. I plan to cover the model with ¼ mil Mylar covering which will be new to me.

Retro Gnome

Texas Timer Micro DT

Sky Demon E20

Ready for covering is a Retro Gnome free flight hi-start glider, the building techniques are not really new to me but I have to setup the auto rudder function. Auto rudder keeps the glider going straight on tow but when tow line releases the rudder moves enough to cause the glider to fly in a circle. I am also using the Texas Timers Micro DT for the first time. This is a mechanical timer which should be more accurate than the viscus and fuse DT’s.  I am also building a Sky Demon e20 model with conventional construction but will use an electronic timer/DT from BSD Micro that I have not worked with before.

Recently I have had some pictures and writing published in model aviation magazines. A couple of mentions in Aeromodeller Magazine published in the UK, the latest issue mentioned my Fantastic Foam Flyer simple rubber powered model and the after school program created by teacher Jon Kemm in the UK. Ronnie Espolt who lives on the US west coast and works with the foam airplanes also was mentioned. Pictures I had taken of 2016 Nats were in NFFS Digest and my description of the Nats was published in November 2016 Model Aviation Magazine. My hope is that getting the name of people that are promoting model aviation for young people and I into media will create more awareness to what we are trying to accomplish.

Bill Kuhl

Related Weblinks    - Wilbur   - Polecat X   - Retro Gnome  Texas Timers Micro DT  - BSD Micro electronic timer/dt for E20 - Sky Demon e20  - Aeromodeller Magazine  - Model Aviation Magazine - Jon Kemm  - Fantastic Foam Flyer